Question

I have a gridview and Textboxes in Form1. When Form1 loads it will load the data into Gridview from database. I have a selectionChanged event of Gridview from where the data goes into textboxes and Now my problem is I want to edit them in Textboxes and save them to database, but When I click on save button it is creating a new record in the database and gridview. How to fix this ?

Below is my code for SaveButton:

private void btnSave_Click_1(object sender, EventArgs e)
{
    DataRow dr = dt.NewRow();
    da = new SqlDataAdapter("select * from Measurement", con);
    SqlCommandBuilder cb = new SqlCommandBuilder(da);
    dr["CellNumber"] = txtCellNo.Text.Trim();
    dr["FirstName"] = txtFirstName.Text;
    dr["LastName"] = txtLastName.Text;
    dr["Shirt"] = txtShirt.Text;
    dr["Pant"] = txtPant.Text;
    dr["DueDate"] = txtDueDate.Text;
    dr["Date"] = txtDate.Text;
    if (dr["CellNumber"] == "")
    {
        MessageBox.Show("Please enter Cell Number");
    }
    else if (dr["CellNumber"] != "")
    {
        dr = dt.Select(" ID = " + txtID.Text)[0]; //updated here
    }

    try
    {
        da.Update(ds, "Measurement");
    }
    catch (DBConcurrencyException ex)
    {
        MessageBox.Show(ex.Message);
    }
}

Code for Gridview:

private void dgv_SelectionChanged_1(object sender, EventArgs e)
{
    if (dgv.SelectedRows.Count > 0)
    {

        foreach (DataGridViewRow row in dgv.SelectedRows)
        {
            //Send the first cell value into textbox'
            txtLastName.Text = row.Cells["LastName"].Value.ToString();
            txtFirstName.Text = row.Cells["FirstName"].Value.ToString();
            txtCellNo.Text = row.Cells["CellNumber"].Value.ToString();
            txtDate.Text = row.Cells["Date"].Value.ToString();
            txtDueDate.Text = row.Cells["DueDate"].Value.ToString();
            txtPant.Text = row.Cells["Pant"].Value.ToString();
            txtShirt.Text = row.Cells["Shirt"].Value.ToString();
            txtID.Text = row.Cells["ID"].Value.ToString();
        }
    }
}

Answer 1

da.Update(ds, "Measurement"); is inserting a new record because the RowState property of the row you are attempting to update is set to Added since you are assigning the cell values to a new row. You need to update the values of an existing row. Check DbDataAdapter.Update Documentation :

When an application calls the Update method, the DbDataAdapter
examines the RowState property, and executes the required INSERT,
UPDATE, or DELETE statements iteratively for each row, based on the
order of the indexes configured in the DataSet

Try this :

private void btnSave_Click_1(object sender, EventArgs e)
{
    da = new SqlDataAdapter();
    da.SelectCommand = new SqlCommand("select * from Measurement where ID = @ID",con);
    da.SelectCommand.Parameters.AddWithValue("@ID",int.Parse(txtID.Text));
    SqlCommandBuilder cb = new SqlCommandBuilder(da);
    da.Fill(ds, "Measurement");        

    if (String.IsNullOrEmpty(txtCellNo.Text.Trim()))
    {
        MessageBox.Show("Please enter Cell Number");
    }
    else
    {
        try
        {
           dr = ds.Tables["Measurement"].Rows[0];

           dr["CellNumber"] = txtCellNo.Text.Trim();
           dr["FirstName"] = txtFirstName.Text;
           dr["LastName"] = txtLastName.Text;
           dr["Shirt"] = txtShirt.Text;
           dr["Pant"] = txtPant.Text;
           dr["DueDate"] = txtDueDate.Text;
           dr["Date"] = txtDate.Text;

           cb.GetUpdateCommand();
           da.Update(ds, "Measurement");
        }
        catch (Exception ex)
        {
           MessageBox.Show(ex.Message);
        }
    }


  }